


Go Fuck Yourself

by singularweed



Category: Undertale (Video Game)
Genre: F/F, Incest, M/M, Multi, Multiverse, Plot With Porn, Underfell, buckle up everyone this is gonna be a wild ride, get it instead of porn with plot, literally the most self-indulgent shit, pure undiluted shenanigans, selfcest, smash all these au's together and get beauty, there'll be a l o t of tags so make sure to check these often, underswap - Freeform
Language: English
Status: In-Progress
Published: 2016-04-06
Updated: 2016-04-24
Packaged: 2018-05-31 14:41:26
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,442
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6474418
Author URL: https://archiveofourown.org/users/singularweed/pseuds/singularweed
Summary: <blockquote class="userstuff">
              <p>Countless timelines. Infinite universes. All a hair’s breadth away from each other. There are names for them- “Underfell.” “Underswap.” “Aftertale.” “Outertale.” Far too many to count.<br/>Have you ever wondered, human, what would happen if those timelines were to collide? If those fragile boundaries disappeared, allowing all the denizens across extensive universes to interact? Does the answer to that question frighten you?<br/>…<br/>God. Fucking. Dammit.<br/>The answer is selfcest. Holy shit. So much fucking selfcest. Seriously, who let these kinky fucks ever meet each other? Honestly, what did you expect? Slam a bunch of horny skeletons together, and assume that they won’t immediately start fucking each other? Please.<br/>So, here we are. Drama, comedy, romance, tragedy, etc., etc., etc.<br/>Featuring the engrossing love story of a nerd and an edgy fuck, the heartwrenching romance between a stoner and a blueberry, the antics of two useless ass skeletons, and much, much, more.<br/>This is a fucking mess.</p>
            </blockquote>





	1. sansapalooza

**Notes for the Chapter:**

> why are there so many of them. who allowed this. they’re all fucking useless shitty ass skeletons what the fuck

With a furious scrawl of letters and a flourish of the pen, the words departed the mind of their creator and came to life. He clenched the notebook in his hand, raising his pen in the other, preparing for another burst of inspiration.

The spiky lettering, written in bold, black ink...

“Standing in the cold, biting winter breeze…

I knelt, and felt the solid earth beneath my knees.

This is the end, the ultimate, the absolute.

After all, is all not moot?”

A pleased smile curled at the lips of the writer, exposing pointed, white teeth and the glint of gold inside his mouth.

A sticker peeled from the journal’s faded, hot pink cover. “Ht Tpic- MewMewNtbookLmtdEdition- $4.99!” Though matted with dirt, the design still showed distinctly. A well-endowed, female human with bubblegum pink hair and cat ears, blowing a kiss into empty space, dainty fingers extended towards the viewer. Though the features were extraordinarily exaggerated- breasts absolutely did  _ not _ work like that- it was still, admittedly, pretty cute. 

The skeleton lowered his pen, huffing slightly at the sight of the cover. From what he’d gathered, the human store…  _ “Hot Topic…” _ It seemed cool. He’d found some other stuff labeled with it in the dump, and they all matched his interests perfectly. Black jackets, t-shirts with demented designs... In fact, he’d found the perfect red eyeliner, and it came from that store. Heh. At least the humans got  _ something _ right. As for the notebook itself, though. 

He ripped the sticker off viciously, crumpling it up and tossing it over his shoulder. Well… he  _ would’ve _ tossed it over his shoulder. However… The sticky backside clung to his finger, refusing to be defeated quite yet. That cheeky price tag… It was  _ challenging _ him, wasn’t it?! He could almost hear it taunting him.  _ Look at me! I won’t let go of your fucking finger!  _ He growled, shaking his hand violently to dislodge it. After several seconds of aggressive wrist flailing, the sticker relented at last. He scrunched up his face in distaste, casting his gaze back to his poetry. Oh well. The notebook would have to do, for now, despite its…  _ interesting  _ design. After all, he needed some way to express his tossing, turning  _ inner turmoil _ .

+-+-+-+-

“Underfell, see… see! That one’s my favorite!”

“He just… Sans just wrote edgy poetry in a  _ Mew Mew Kissy Cutie  _ notebook from  _ Hot Topic _ .”

A flash of a grin.

“Your point is?”

A heavy sigh.

“Let’s just look at the next one, alright? Underswap… it’s a cool one!”

+-+-+-+-

“No, no, but get this, Sans, get this. What if- hear me out here- If you weighed 99 pounds, right. And you ate one pounds’ worth of tacos. You’d be one percent taco.” The skeleton on the couch stared listlessly into the distance. “Do you think I could drink a whole pound of spaghetti sauce, Sans? Can I become one percent spaghetti sauce? I think I can. Wait, shit. Do I weigh 99 pounds?”

_ Crack! _ The hard tortilla shell snapped, sending crumbs flying across the table.

“Brother, please, must we do this every time I make tacos?” 

Papyrus stared at the broken shards of taco shell scattered across the table. He picked a piece up.

“Nyeheheh- pfft, look, Sans. It looks like a dick.” He held it up to the light, examining it at a multitude of different angles. Sans huffed, tapping his foot.

“Language!”

“Seriously. Look at it.”

“I refuse!”

“Eh, your loss.” The phallic shaped taco shell disappeared into Papyrus’ mouth in an instant.

_ Crunch! _

“Bro. Bro, do y’think… mm,” Papyrus spoke, his mouth still brimming with taco dick shards. “Do y’think slang is just slang for ‘short language?’ Damn.  _ Damn _ .”

+-+-+-+-

“Okay, that’s enough of  _ that  _ one!” 

The other child pouted. “But Core… He’s  _ cool _ ! That Papyrus is super cool!”

“Nuh-uh! Classic is  _ way _ better! Plus he doesn’t have any of that gross happy grass stuff!”

“Bleh! Underswap Paps is the  _ best! _ ”

The other child plugged their ears, puffing out their cheeks. “La, la, la! I can’t hear you!”

“Core is being a meanie!”

“No, Hacker is! Meanie! Meanie!”

“Ahem. Children, children, I’m sure all Papyruses are very, very cool. But speaking of the ‘classic’ universe… Let’s take a peek, shall we?”

+-+-+-+-

_ Snore… Snore… _

Empty ketchup packets littered the floor of the room. Dull light filtered in through the window. On the floor, leaning against the pitiful excuse of a mattress, was a skeleton. His aesthetic was truly exquisite.

A stained, wrinkled hoodie, that hadn’t been washed since… Well, better not discuss that.

Greying bunny slippers. They’d been pink, once upon a time.

The small trail of cerulean drool leaking from the side of his mouth.

Our very own beloved skeleton, the one and only, the man, the myth, the legend: Sans.

…

What? You were expecting more? 

Nah. That’s it. He’s just passed out in a pile of empty ketchup packets. That’s it. That’s all.

“Sans! I am entering your room! It’s time for work, you lazybones!”

...Oh?

After some wrestling with the door handle, Papyrus strode into the room. He glanced around, eyeing the filth  and socks at every turn. He tutted. “Come on, brother. You really should clean up some time.”

“Mmmh… Oh, hey, bro.” Sans cracked one eye open minutely, watching his brother refill his drawer with clean socks. Sans yawned. “Work…? Oh, yeah, that.”

Papyrus closed the drawer and brushed himself off. “Yes, work! Don’t tell me you forgot again!”

A hand waved lazily at Papyrus. “I was on leave last time, ‘s fine.”

“You always say that!” Papyrus crouched next to Sans. He tilted his head. “Really, brother. Let’s go.”

Sans’ one open eye began to drift shut.

Suddenly, two arms were around him. He was scooped up quickly and easily, his feet leaving the floor and hanging in the air. One of Papyrus’ arms supported his thighs, while the other held his back. He was, put simply, being carried bridal style.

“That’s enough lazing around! Nyeheheh! Let’s go!”

+-+-+-+-

“Well…! That wasn’t so bad, now was it?”

“It only proves my point! He was asleep and boring and  _ lame _ until…  _ Papyrus _ showed up! Proving he is the best Papyrus!”

Hacker blew a raspberry in the other Frisk’s direction.

The man laced his fingers together and inhaled. “Hey! Stop that! Stop bickering, you two!”

“They started it!” The children exclaimed in unison.

Gaster sighed. If he had a nose, he would’ve been pinching the bridge of it. However, as both a skeleton and a being of the void comprised mostly of vaguely goop-like substance, it just wasn’t possible.

“How about we move on from that! Maybe we can look a little in the past. That would be more interesting, yes?”

A head popped up beside Gaster. They stared at him with wide, empty eyes and a blank expression. Suddenly, they broke out into a smile. “In the past? Let’s do it!”

+-+-+-+-

“Alph, Alph, okay, but listen to this one: What would you say if I froze myself to  -273℃?”

“Um… You’d, uh, die?”

“No, of course not! I think I’d be…”  _ Wink _ . “Perfectly 0K.”

Papers shuffled on the table. The skeleton nudged his lab partner. “Get it, Alph? 0K. Zero Kelvin. Okay.”

“I… I get it, Sans. J-just get back to work.” With a clatter of her pen on the workbench, Alphys stood up abruptly. “I’ll be getting to, er, other business, now!”

“Aw, c’mon! Was it really that bad?” Sans spread his hands. “I have more! I was just  _ warming up _ with that joke, heh-”

“Y-yes, quite! Mhm, yup! I’m really busy, Sans! See you!” Just like that, she was gone.

Sans pursed his lips and pushed up his glasses. “Huh.  _ I  _ thought it was pretty good.”

He looked back down at the file he was currently reading, twirling his pen in his fingers.

“Universe mechanics, pt. 1:  _ Anomalies. _ ”

+-+-+-+-

“Hey, that’s us! We’re the anomalies!”

“Yeah, that’s us. But that sounds so  _ lame _ . I think…” They posed dramatically. “ _ Judges of the Void  _ sounds cooler.”

Core stared at the other Frisk. “That’s super lame, too! I think we should be… The Deliberators of Fate.”

“Nope. Judges of the Void.”

“ _ Deliberators of Fate. _ ”

“ _ Judges. Of. The. Void. _ ”

“Deliberators of-”

“Children, please… We’re the anomalies, remember?” Gaster cleared his throat. “Back to the topic at hand, however! So, now that we have reviewed the universes of choice, do you two still hold your position?”

Hacker tutted. “Of course we do, Pops. Things are getting  _ boring _ . We need something new! Something exciting! Something totally  _ not-lame _ !”

Core nodded slowly. “Yep, not-lame would be good.” They scratched their head. “But we need to keep the balance between us, right? How will we decide what to do? What to create?” They waved their hand into the abyss, splitting open small fissures of movement and color. 

The windows to the different universes flickered in the void, like old television screens ripping through the fabric of space. The denizens of each bustled about, blissfully unaware that they were being watched, and also blissfully unaware of the universes running parallel to their own. 

Gaster clapped his hands together. “Well, I thought we would have a little bit of fun! I know you two enjoy your…  _ virtual games _ , as kids call them nowadays, but I figured we could go back to the basics!”

He reached into empty space, groping into nothingness as if looking through a cluttered bag. 

The Frisks looked at each other, smiles creeping up on their faces. “A game, huh? To decide what new universe will be made?”

“Yes, indeed. A game. A game that spans throughout the ages, a game so full of fun and mystery and thinking that the winner truly will be the right one to make the choice!”

Core leaned over Gaster’s shoulder, trying to peer into nothingness. “What… what game?”

Gaster flourished his hand expansively, causing Frisk to stumble a few steps back. A wide grin stretched across his face. In his hands, he brandished a set of multicolored, tattered cards.

“UNO!”

**Notes for the Chapter:**

> that's right. multiverse fic started off with fucking uno. thanks, void dad.  
> kudos and comments are really appreciated! thanks for reading this shit. it'll be big. and gay. big gays. fontcest, sanscest, and all that.  
> prepare your asses for shenanigans.  
> make sure to stop by smoochthemskeles.tumblr.com. i'll be there.


	2. a game of cards

**Summary for the Chapter:**

> everything has a beginning. humble beginnings, dramatic beginnings. you’d think the beginning of an all-encompassing multiverse would be pretty impressive, huh? especially when it involved two all-knowing beings of the void and an all-powerful, world-breaking entity.  
> wrong.  
> it all started with a fucking game of cards.

**Notes for the Chapter:**

> i'd apologize for using sans'... unique... poetry twice in a row. but i'm not sorry. not sorry at all.  
> also, check out this fucking fantastic art of hacker!frisk here, in case any of you need an idea of what they look like: http://samplefrisks-edu.tumblr.com/post/143154806973/my-friend-requested-their-hackerfrisk
> 
> shit's going down.

The void was, first and foremost, empty. There was no sound of static. Sensation didn’t exist. Just empty, empty, empty. Complete absence of white noise, of feeling, of atmosphere. Silence. Except for--

“Aha! Add four cards! My _secret_ weapon. Victory is surely mine.”

Ah, yes. Empty. Except for the omnipotent, brilliant fallen scientist, currently playing an overrated _card game_ with two children. A card game that happened to determine the fate of multiple worlds.

Gaster rubbed his hands together gleefully. “Are you two ready to admit defeat? Then we’ll finally…” Gaster’s eyes shimmered. “At last, we can create a universe where I exist!”

“Mhm, that’s great, Pops,” Hacker said, reaching out their hand into the void. “Thanks for the cards! Now that my turn is skipped, I have time for…” A tattered notebook plunged out of empty space and landed in their outstretched hand. A faded label stuck weakly to the back. “COLOR: MOONLIGHT EBONY.”  They grinned. “This is the stuff! Ahem. Another excerpt from Underfell.” They flipped through the dusty pages to a random page.

“The darkness overwhelms me, body and mind… In this eternal abyss, what is there to find?”

Core oohed and clapped. “That one was actually decent!”

“All of them are good!” Hacker huffed. “It’s _art_ , Core.”

“If you wanna see art, you should read Alphys’ fanfiction--”

“Children, please desist. You are distracting from this game of wit. How am I supposed to concentrate with that absurd poetry ringing in my ears?”

Hacker and Core shared a knowing look.

Core smiled. “Okay, okay. My turn, then!”

They looked at their hand of multicolored cards. A wistful sigh escaped them. They spread their greyscale fingers. Ah, memories. Fond memories, back when color existed.

“Okay!” Core said. “I’ll use reverse, here, so that it’s Hacko’s turn again.”

“Child, did you just call them ‘Hacko-’”

Hacker piped up. “Yes, _finally!_ I wanted to use this one! Color change… _and plus four._ Eheheheh!” Hacker’s sharklike grin widened across their face. “You don’t stand a chance, Pops.”

They paused, contemplating something.

“Color change…” they muttered under their breath. “That’s a good idea!”

Hacker stretched their arms up above their head, cracking their knuckles and craning their neck. They shook themself out like a dog flicking water off of its fur. Their body began to ripple and change color, glitches erratically ripping through their form. The distorted colors of the rainbow rippled over them. The hues blinked and quivered, going awry without rhyme or reason.

Core looked upon the vibrant colors, sticking up their nose with a hint of jealousy.

Hacker glanced at them and winked exaggeratedly. “Oh, but that’s not all!”

Small, glowing white LV and HP bars popped into existence with a distinct _vwop!_

**LV: ???**

**HP: ???/???**

They twinkled and blinked out of view, before springing back, even brighter and… neon? They flashed in tandem with Hacker’s oscillating body.

**LV: 666**

**HP: 420/420**

They flashed a smile of triumph. Blue and red shimmered over their teeth.

“See?” they exclaimed. “Color change!”

Hacker arms stretched out towards Core, fingers wiggling. “Psst. Pass the poetry, here.”

The other Frisk exhaled. “Okie dokie.”

Gaster’s mouth twitched in annoyance. “Children, is this really necessary? And Hacker, those numbers are _highly_ inappropriate. Where are you learning th-”

“‘We snarl and claw, we do what we must. All because we know: they’re onto us.’ Ehehehe! I like that one! It sounds like… A super important title.”

Hacker gestured expansively in front of them with one hand. They bowed their head dramatically, bangs shielding their eyes. With a flick of their wrist, they brought an imaginary microphone to their mouth. “They’re onto us.”

Core gasped, struck by a sudden premonition. “Ooooooh. That’s his blog title.”

“His wha-”

“Y’know, his aesthetic blog that he’ll create in approximately-”

“Blah, blah. Okay, don’t need to know.” Hacker’s fingers flapped, imitating a blabbing mouth. “All knowing, all seeing, _whatever_. Let’s keep playing.”

Gaster sighed heavily. “Who is teaching you these things?”

Core opened their mouth. Realizing the basic error in his rhetorical question, Gaster hurriedly shushed them.

“Omnipotence is a privilege! Do not abuse it, child!”

Core’s arms crossed and they regarded him skeptically.

“And no sass! Honestly, you two should be more responsible than this, considering your experiences, it’s simply appalling…”

Small, fractal glitches blurred Gaster’s hands. Hacker stifled a giggle, waving a hand at Core. Their message was clear: _keep distracting him_.

That hardly needed more work. Gaster was so caught up in his rant about void duties and anomaly responsibilities he didn’t even notice the cards disappearing one by one from Core’s deck. He didn’t notice them appearing in his deck.

At last, Core was left with only one card.

Color change.

Hacker winked. Core returned their notion with a small, knowing smile.

“Oh, whoa!” Core blurted out. “Would you look at that!”

They held the card between their index and middle finger. “Uno!”

“What--”

Core delicately placed their card on top of the pile. “Looks like I win!” They smiled innocently, corners of their eyes crinkling up. “What a good game.”

Hacker blew a strand of hair away from their mouth. “Yup, mhm.”

The pile of cards floated innocuously in the void. If looks were piercing, the cards would have a gaping hole in them from Gaster’s troubled gaze.

“I don’t understand; I could have sworn that-”

Hacker stuck their tongue out and grinned at him. “Maybe you’re getting senile, old man!”

“Why, I never-!”

Core nodded sagely. “I’ll have to agree, there. A deal’s a deal. I win, so I get to decide what we’re doing next.”

Gaster breathed in, ready to protest again. “Please, I just want to exist-”

“You know that can’t happen, Pops,” Core tutted.

Hacker was wordless. They glided over to Gaster, placing a hand heavily on his shoulder. They closed their eyes, shaking their head. “That’s rough, buddy.” Their head snapped back up abruptly and they shot a cheery smile at Core. “Hehe! Take it away!”

Gaster’s eyes flicked back and forth between the two Frisks, who were exceedingly congenial with each other. “You two are getting along surprisingly well-” He gasped. “Wait… No… You didn’t _plan thi-”_

A loud clearing of the throat interrupted Gaster mid-sentence. Core straightened their back, clasping their hands behind them.

“Ahem! Now,” Core began. “I think this prospect will be very… Fun! Which is rare.”

Hacker booed. “No rambling! Get on with it!”

“Hehehe…” Core beamed. “You know what’s coming, too, though, Hacker!”

Hacker rubbed their hands together. Core kneaded their pointer finger and thumb together by their mouth, as if pinching an imaginary, villain-esque mustache between their fingers.

Gaster looked on in horror.

Core spoke, their voice quiet and dramatic.

“So. What would you think about a universe where…”

Hacker completed their sentence. “The boundaries between different universes were gone?”

Comprehension dawned on Gaster’s face. Core continued.

“Where everyone-”

“Everyone!” Hacker echoed.

“Got to be best of buds,without restriction?”

“That’s right.”

The children spoke in unison.

“A multiverse.”

+-+-+-+

The sound was like a _snap!_ , ringing in the collective ears of everyone in the Underground.

It was loud, and piercing, like a sharp pain.

It happened when Sans was at his sentry station. The squeezed bottle of ketchup precariously balanced at the edge of his table wobbled. The world shook again. It dropped, rolling into the snow. Vibrations from the earth sent shocks throughout the weak wooden structure of his station.

Sans’ eyes shot open. He definitely wasn’t nodding off, now.

His eyes focused on the snowy landscape around him. Nothing seemed amiss, except for the fact that the monsters near him were hunched together and muttering in trepidation. Seemed it wasn’t his imagination.

Another _snap!_

A tree started to turn wavy.

Sans rubbed his eyes.

Nope. Still wavy.

_Snap! Snap!_

If worlds breaking had a sound, this was it.

He looked down at his hands.

Well, what do you know. They were wavy, too. His fingers blurred together, making it impossible to tell where one began and the other ended. He sighed. This was certainly somethi--

Suddenly, a single word interrupted his train of thought.

_Papyrus_.

_Sans_ was okay, but Papyrus could be in trouble, and he had to get to him right away; they were so close to being free, he couldn’t let something bad happen, not _now,_ not after they made it so far-

This was no ordinary event. It wasn’t just the kid resetting; he’d gotten used to that boring, numb feeling by now. No, this was something different, and it looked like he had to get off his ass for _once_. He stood shakily, looking left and right before taking two shaky steps-

_SLAM!_

Someone crashed into him at full force.

“Sans! Are you okay?”

Papyrus stepped back, steadying Sans with both hands and scanning his face worriedly. “You’re not hurt, are you? Your fragile lazybones body could’ve been damaged by this very unusual event!”

“What, no, I’m fine--” Sans shook his head. “No, wait. How did you get here so fast?”

His brother puffed up his chest. “Just like Undyne does! I _ran-”_

Of course.

“To check if you were safe! You are fragile, Sans, and with this extremely odd occurrence there would be a high possibility you could have been harmed! Honestly, you should exercise more; you’re almost as bad as the snails at that ghost’s house!”

“Heh, right, that’s me, _Snans_ , or Snail Sans-- _Fuck!_ ”

_Snap!_

A searing pain shot through Sans’ head, and he hunched over. He heard a pained gasp next to him. Passerby all around them dropped to their knees simultaneously.

Sans groped blindly, eventually feeling what felt like Papyrus’ hand. He clung onto it tightly. The pain was blistering, but as long as he knew he was safe, then--

_Snap! Snap! Snap!_

The agony stopped, replaced with a different feeling.

Fluidity.

It was a flowing, open sensation, like floating freely in a large body of water. The oppressive, claustrophobic atmosphere of the Underground lessened. Sans gasped in a breath of air. His vision blurred; he was still disoriented. Chaotic, indiscernible chatter rang in his head. If he concentrated, they almost sounded like voices.

The voices melded together, first speaking in unison, then dissolving into… Laughter?

Giggling, even.

Like the laughter of a child.

A young voice spoke in Sans’ mind, overlaid with the fuzzy sound of static.

Papyrus turned his head to Sans. His eyes were wide.

“Do you hear it, too?” he mouthed.

Sans nodded.

The voice spoke to the brothers, and to the minds of all in the Underground, _entirely_ too cheerily.

“Welcome to the multiverse, everybody!”

The laugh rang out once more.

“Enjoy!”

**Notes for the Chapter:**

> special thanks to my pal samplefrisks-edu.tumblr.com for the visuals!  
> there we have it for the introduction, folks. don’t worry, after this, we’ll be delving into the actual interactions between characters, and significantly less of the void trio. an important thing to note: chapters after this point will be posted out of chronological order, but will be titled by ships and/or events. eventually i’ll be making a masterpost in case you want to read all of them in chronological order.
> 
> Coming up next… Gayman Origins.  
> The intellectual and the warrior, the glasses and the teeth, the ratty labcoat and the black jacket.  
> That’s right.  
> Edgelord and nerd, coming right up.


End file.
